I'd already learned that, to be able to remember's people's names later, I had to make an actual effort to repeat their name to myself while I was looking at them. So, I then started consciously trying to notice details about people's appearance when I first met them - what's their hair color, what color are their eyes, what are they wearing and carrying. Eventually, this effort became a habit. Now, I usually do this automatically when I first meet someone, and I remember more of those details.